i didnt check this, but you got the answers to be roughly -0.1 right. so we want n so that -1/n^2 = -0.1. so idealy we want n^2 = 10. since -1/10 = -0.1. but that would mean n = sqrt(10) which is not an integer. so the closest we can get is say, n^2 = 9. so -1/n^2 = -1/9 = -0.111111111... so then n=3